Lawn care is a major business in the United States. Every year, billions of dollars are spent on feeding, mowing, and grooming lawns. One of the most common lawn care tasks is the spring thatching of the lawn. In the spring, the turf tends to be matted down after the winter snowfall. The underlying soil is packed tightly, reducing proper drainage (the packed soil does not allow water to percolate through to the grass roots) and preventing the proper movement of air through the lawn. Leaves and other debris also cover the lawn. Thatching is a process that removes the debris from the lawn, opens the blades of grass, and when done properly, aerates and loosens the underlying soil. Thatching promotes faster growth in the lawn, improving its appearance and health.
There are many products used to thatch lawns. A hand rake may be used, but besides being very strenuous, the results are, at best, superficial. Several power rakes have been developed that make the work less toilsome. These power rakes also tend to do a more thorough job in cleaning the lawn and in aerating the soil Examples of these devices are found in U.S. Pat. Nos. 3,611,691 to Howard; 3,724,182 to Long et al., 3,742,688 to Tonjes, Jr.; 3,753,341 to Berg, Jr. et al.; 3,918,242 to Harris; and 4,578,938 to Genesco. Howard teaches a rake attachment for power mowers. The primary purpose of this device is to rake the cuttings from a lawn during the cutting process. It can also be used to pick up debris. The Howard device has a number of tines bolted to a blade. There are three tines placed at the outer edges on each side of the blade (six tines in all). The tines work the turf in the same mariner as a hand rake, except that the tines are driven by an engine. The Long et al. design has a pair of oppositely disposed paddles bolted on the ends of a blade for mowers. The Long et al design is intended as a leaf, grass or loose snow blower. Moreover, Long teaches the addition of tines that act as a scarifying member to renovate lawns. The Tonjes, Jr. patent teaches a pair of oppositely disposed hinged tooth carriers. These carriers are held in position by aerodynamic force. Again, tines are used to work the turf. The hinges allow the tines to be moved if a hard object is hit. The Berg, Jr., et al., patent leaches use of a pair of polyethylene rake units that are mounted on a form that is used in place of a blade. Finally, the Harris design uses a pair of tine units to rake the grass. Here, the tines can rotate from a retracted position to an extended position as the blade, on which the tines are mounted, rotates.
All of these inventions have one common problem: they all use some form of metal tine system, similar to that of a hand rake. These tines, when attached to a power mower tend to rip the turf as the power mower turns the blades. Hand raking uses similar tines, but there is no way for a person to exert the force that a power mower can exert and there is no way a person can match the speed at which the tines contact the grass. Of course, if the device is not set properly, e.g., too low, the tines dig the turf up, perhaps killing it in spots. Even at low speeds, the metal tines on these blades do more damage than a hand rake ever could do.